The 100 Myr Star Formation History of NGC 5471 from Cluster and Resolved Stellar Photometry

TL;DR

This study reveals that star formation in NGC 5471 has been ongoing for at least 100 million years, with complex history and spatial distribution, using multi-wavelength photometry and resolved stellar analysis.

Contribution

It provides a detailed 100 Myr star formation history of NGC 5471 through combined cluster and resolved star photometry, revealing complex temporal and spatial patterns.

Findings

Star formation in NGC 5471 has persisted for over 100 Myr.

The region shows multiple star formation episodes at different ages.

A large bubble likely formed by stars from a major event less than 20 Myr ago.

Abstract

We show that star formation in the giant HII region NGC 5471 has been ongoing during the past 100 Myr. Using HST/WFPC2 F547M and F675W, ground based JHKs, and GALEX FUV and NUV images, we have conducted a photometric study of the star formation history in the massive giant extragalactic HII region NGC 5471 in M101. We perform a photometric study of the colour-magnitude diagram (CMD) of the resolved stars, and an integrated analysis of the main individual star forming clusters and of NGC 5471 as a whole. The integrated UV-optical-nIR photometry for the whole region provides two different reference ages, 8 Myr and 60 Myr, revealing a complex star formation history, clearly confirmed by the CMD resolved stellar photometry analysis. The spatial distribution of the stars shows that the star formation in NGC 5471 has proceeded along the whole region during, at least, the last 100 Myr. The current ionizing clusters are enclosed within a large bubble, which is likely to have been produced by the stars that formed in a major event < 20 Myr ago.